What should I look for when buying a refrigerator water filter?
If it's safe to drink, you'll want to make sure any refrigerator filter you use at least passes NSF's material safety and structural integrity tests under NSF/ANSI 42. Because if it doesn't, it could be doing more harm than good. What should I look for in a refrigerator water filter? NSF Testing and Verification
NSF 42: Any water filter worth its salt will have, at the very least, an NSF 42 certification.